Nettle (Urtica dioica) supplementation: impact on growth, hematology, immune response, and resilience to Aeromonas hydrophila in Labeo rohita fingerlings

The significance of plant-derived products in aquaculture lies in their potential to offer sustainable alternatives, promoting eco-friendly practices. This study investigated the impact of nettle (Urtica dioica) leaves powder on the growth efficiency, hemato-biochemical variables and non-specific immune system of rohu, Labeo rohita fingerlings. To achieve this objective, sample average weight (5.23 ± 0.34 g) were categorized into four groups, namely control, T1, T2 and T3 in triplicate and administered diets fortified with nettle in amounts of 0, 1, 3 and 5% respectively for a duration of 60 days. After 60 days of fortified diet, the fish underwent intraperitoneal injection with bacteria (Aeromonas hydrophila), and subsequent relative percentage survival (RPS) was observed. The growth performance, including “weight gain (WG), specific growth rate (SGR), feed conversion ratio (FCR) and feed efficiency ratio (FER)”, were notably higher in the T3 group (5%) than in others. The hematological values of White blood cell, hematocrit, and hemoglobin revealed higher levels with a fortified diet. The dietary supplementation of nettle reduced serum cholesterol and glucose concentration, whereas it increased albumin, globulin, and total protein in the fish blood. Enhancements in lysozyme and myeloperoxidase activity were observed in the intervention groups with feed containing nettle supplementation. The nettle diet at a 5% concentration demonstrated a higher RPS than the others following injection with A. hydrophila. The findings indicate the potential of nettle as a valuable nutritional supplement for increasing fish immunological reaction and bolstering pathogen resistance.